General Softstart Strategy of Bi-Directional Buck/Boost by Feedforward Control Based on Average Current Mode

The buck/boost converters are widely used in bidirectional power flow application. High inrush current exists in the start-up process by traditional control strategy due to the loss of voltage second balance when both sides are voltage sources. In this paper, a general soft-start strategy of buck/boost in continues current modulation and triangular current modulation by feedforward control based on average current mode is proposed, which guarantees the voltage second balance during the operation, and eliminates the inrush current during the soft-start process. The proposed control can also be adopted to improve both steady and dynamic performance. Finally, a 300W experimental prototype has been built to verify the effectiveness of the proposed control strategy.